How to Use QEMUs “debugcon”-Feature (and Write Debug Infomation to the Terminal or a File)

QEMU is a VMM often used for low-level OS/kernel development and testing. Especially when you write your own OS/kernel, things can get really hard and difficult to debug. Furthermore, there are not many debug capabilities, as you can’t write to files or print to the screen in early boot phases, thus, without loaded drivers. For these cases, QEMU has a featured called debugcon. It is not as good/prominent documented as it should be, Read more…

Rust: setTimeout and setInterval as in Javascript with “tokio” as Runtime

Even though I’m working with Rust for over 2.5 years now, I unfortunately never made a deep dive into the async/await/future-world. But I started using tokio a few days ago and a few questions came up. Tokio is a runtime for executing futures, great! For this, tokio needs some kind of “tasks” or “lightweight userland threads”, okay. To schedule N tasks across M cores, tokio need some kind of event loop,.. so.. similar Read more…

How-To: Compile EDK2/OVMF From Source on Linux [2021]

EDK2 is a development environment to create firmware implementations that follows the UEFI specification. It is part of tianocore project. which is the reference implemenation for UEFI. Multiple “packages”, which are the sources to build tianocore for different platforms (x86, ARM, QEMU), are located inside the git repository of “EDK2”. OVMF, which stands for Open Virtual Machine Firmware, is one of these packages. It enables UEFI inside virtual machines, like in QEMU environments. Read more…

Frequency Spectrum obtained using my Rust lib (original signal: sine waves at 50, 1000 and 3777 Hz with a little bit of clipping, which results in the noise in the signal)

Frequency Spectrum Analysis with FFT in Rust (library spectrum-analyzer)

One week ago FFT (Fast Fourier Transformation) and frequency spectrum analysis were still a mysterium to me. Because I have a long time planned side project (live beat detection to music) and had some time, I started to make a deep dive into digital signal processing (DSP), including lowpass filters and especially frequency spectrum analysis using FFT. I was a little bit shocked/disappointed by the lack of good ressources and easy to understand Read more…

Effective + Simple Way to Manage & Obtain Multiple Let’s Encrypt Certificate for Different Domains Using a Small Shell Script

Yesterday I faced the problem that I need a convenient way to manage multiple domains on the same host/IP. I have “main” domains with potentially further sub-domains. How can one optimize the retrieval of certificates without writing all the shell commands manually or look ’em up in the shell history? I asked myself this question and came up with this solution, not sure if my solution is ideal but it is effective and Read more…